[Show abstract][Hide abstract]ABSTRACT: We have determined the frequencies of human leucocyte antigen (HLA)-B*57:01, HLA-B*35:05, HLA-C*04 and HLA-C*08 in healthy individuals of South African Indian (SAI) ethnicity (n = 50) and South African mixed (SAM) ancestry (n = 50) using real-time allele-specific polymerase chain reaction (AS-PCR) assay. HLA-B*57:01 associates with immune hypersensitivity reaction (IHR) in individuals exposed to abacavir (ABC), while nevirapine (NVP) IHR associates with HLA-B*35:05, HLA-C*04 and HLA-C*08. Real-time AS-PCR assays typically use less DNA, are more cost-effective and rapid compared with conventional genotyping methods, such as sequence-based typing (SBT). The assay was developed using samples of known HLA class I genotype and subsequently applied to the SAI and SAM samples. HLA-B*57:01 was detected in SAM and SAI populations at frequencies of 8.0% and 12.0%, respectively, while HLA-B*35:05 was not found in SAI individuals, but was present in 6.0% of SAM individuals. HLA-C*04 was detected in 22.0% and 24.0% of SAM and SAI individuals, respectively, while 10.0% and 8.0% of SAM and SAI individuals, respectively, were HLA-C*08 positive. This study reports the development of a novel real-time AS-PCR assay to identify HLA class I alleles associated with ABC and NVP IHR and has established the frequencies of these alleles present in healthy SAI and SAM populations. Using South African demographic data, our hypothetical analysis suggests that a substantial number of individuals would benefit from the assay.

[Show abstract][Hide abstract]ABSTRACT: BackgroundHLA-B*58:01 is associated with allopurinol-induced severe cutaneous adverse drug reactions (sCADR) particularly in Han Chinese, but the risk in European populations has seldom been studied. Objective
To study the association of HLA-B*58:01 with allopurinol-induced sCADR in a Portuguese population. Methods
We studied 25 patients (11 male/14 female, mean age 67·4 years) with sCARD from allopurinol: 19 DRESS (drug reaction eosinophilia and systemic symptoms) and six Stevens–Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). HLA was genotyped by reverse sequence-specific oligonucleotide–polymerase chain reaction and results compared statistically with a control group of 23 allopurinol-tolerant individuals and the control population. ResultsHLA-B*58:01 was present in 16 patients with sCADR (64%) [12 DRESS (63%), four SJS/TEN (67%)], one allopurinol-tolerant individual (4%) and 63 normal controls (1·96%), with a statistically significant difference between sCADR and the two control groups. When compared with the normal population, HLA-B*58:01 was associated with a higher risk of sCADR, both DRESS [odds ratio (OR) 85·36, 95% confidence interval (CI) 32·52–224·04] and SJS/TEN (OR 99·59, 95% CI 17·91–553·72). There was no statistically different risk between these two types of CADR. Conclusions
Portuguese patients with sCADR from allopurinol, both DRESS and SJS/TEN, have a high frequency of HLA-B*58:01, with an OR similar to European patients with SJS/TEN. This study also extends this association to DRESS in Europeans. The recommendation to genotype systematically before therapy is controversial, particularly when HLA-B*58:01 prevalence in the normal population is low, as in Europe. However it could be an option for patients with other risks factors.

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